Recent advances in micro-electronics, chemical sensors, and electroanalytical chemical methods are combined to produce a new capability for personal exposure monitors (PEMs). Personal exposure monitors have been shown to be effective tools for the determination of human exposure to a variety of toxic agents in outdoor, in-transit, and indoor micro-environments. The small PEMs to be developed herein include a computer for instrument control as well as data logging. The sensors utilize differential electroanalytical methods so that increased versatility, sensitivity, and selectivity can be achieved in a small low-power sensor. The impact of modern electronic and chemical sensor technology on the health sciences is assessed especially with respect to the assessment of human exposure to toxic agents (airborne). The research is significant because it has implications for the development of micro-instrumentation that can be used in wide variety of applications.